In integrated circuits, weak transistors that have smaller drive currents than other transistors on the same chip, are sometimes needed. To form a weak transistor, two or more transistors of the same conductivity type may be connected in series, with the source of one of the transistors connected to the drain of the other transistor.
The layout of the two transistors that form the weak transistor typically include a rectangular active region. Two gate electrodes are formed over the active region and parallel to each other, and form two transistors with the underlying portions of the rectangular active region. The gate electrodes may be interconnected through a connecting portion that is not directly over the active region. Accordingly, the connected gate electrodes in combination form the gate electrode of the weak transistor, and the active region on outer sides of the gate electrodes form the source and drain regions of the series transistor. The portion of the active region is shared by two transistors as the common source/drain region.